[Edworld]

You need to have an OMDB API Key.
You should donate 1USD to https://www.patreon.com/bePatron?u=5038490.
And then request your pesonal key via email http://www.omdbapi.com/apikey.aspx

Don't forget to delete your simplecache.db

Rotten Tomatoes, IMDB and Metacritic are confirmed working.

I've entered both my TMDB and OMDB API keys, but get no results for either Rotten Tomatoes or Metacritic even when simplecache.db
is deleted. I'm getting IMDB ratings even if no API keys are entered.

my guess is that you are getting IMDB from Kodi not skinhelper.

I assume you have Marcel's repo installed, if yes, install his greatest Titan skin and see if you are getting ratings